Dug a trial pit - help!

[MustyandConfused]

Have structural engineer coming out in a couple of weeks for site visit related to our application for an extension. 
 

He’s asked for two trial outs to be dig to expose existing foundations 300x300 and dig to 50mm below underside of foundations. 
 

I thought I’d give it a go - how hard could it be, right? 😃

 

so first pit was to be in corner where our conservatory (built 20 years ago and to be demolished to make way for new extension) meets the original house wall. 
 

I was expected to hit the top of the foundation about 400-600mm down. However, if I’m looking at it right, it’s only about 250mm below ground level - as are the founds for the conservatory. Both seem to be around 150mm thick (which is what I expected). 

 

in addition, the house founds seem to be brick rather than a concrete strip (again to my eyes at least). House is an early 1930’s bungalow. 
 

a) am I looking at it right - going by the pics? (I put the wooden skewers in to mark where I think bottom of founds are)

 

b) is this likely to be an issue re new extension?
 

 

 

 

[MustyandConfused]

Another pic 

[Nickfromwales]

You have what you have, so let the SE come out and advise you accordingly . Just relax and follow the process.

[nod]

Conservatory foundations tend to be very shallow as they are not taking much weight and are unregulated 

 

[MustyandConfused]

1 hour ago, nod said:

Conservatory foundations tend to be very shallow as they are not taking much weight and are unregulated 

 

Thanks. Should have mentioned conservatory was built with planning / building standards permission (although 20 years ago). I actually still have the paper plans for it (very unlike me!)

 

[nod]

SE will tell you to dig a deeper strip foundations 

[saveasteading]

7 hours ago, nod said:

SE will tell you to dig a deeper strip foundations 

My house is on 400 deep footings. It's my job, but I got another SE contact for a second opinion.....he said it's been here 80 years so its going to be ok for another 80.

But I didn't need anything in writing.

 

Depends also on the ground type and any nearby trees.

 

If yours wants deeper found's for the new extension that is to be expected.

If they want underpinning of the existing, then try to persuade them otherwise, using the 100 years principle.   In fact it may be best left alone.